[tip:perf/core] perf cs-etm: Configure contextID tracing in CPU-wide mode

From: tip-bot for Mathieu Poirier
Date: Mon Jun 17 2019 - 15:25:32 EST

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Commit-ID: 3399ad9ac234364396f75531203c38be5d2872c7
Gitweb: https://git.kernel.org/tip/3399ad9ac234364396f75531203c38be5d2872c7
Author: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
AuthorDate: Fri, 24 May 2019 11:34:52 -0600
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 10 Jun 2019 15:50:01 -0300

perf cs-etm: Configure contextID tracing in CPU-wide mode

When operating in CPU-wide mode being notified of contextID changes is
required so that the decoding mechanic is aware of the process context
switch.

Signed-off-by: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Reviewed-by: Suzuki Poulouse <suzuki.poulose@xxxxxxx>
Tested-by: Leo Yan <leo.yan@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Suzuki Poulouse <suzuki.poulose@xxxxxxx>
Cc: coresight@xxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/20190524173508.29044-2-mathieu.poirier@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/arch/arm/util/cs-etm.c | 126 ++++++++++++++++++++++++++++++++------
tools/perf/util/cs-etm.h | 12 ++++
2 files changed, 119 insertions(+), 19 deletions(-)

diff --git a/tools/perf/arch/arm/util/cs-etm.c b/tools/perf/arch/arm/util/cs-etm.c
index 911426721170..3912f0bf04ed 100644
--- a/tools/perf/arch/arm/util/cs-etm.c
+++ b/tools/perf/arch/arm/util/cs-etm.c
@@ -35,8 +35,100 @@ struct cs_etm_recording {
size_t snapshot_size;
};

+static const char *metadata_etmv3_ro[CS_ETM_PRIV_MAX] = {
+ [CS_ETM_ETMCCER] = "mgmt/etmccer",
+ [CS_ETM_ETMIDR] = "mgmt/etmidr",
+};
+
+static const char *metadata_etmv4_ro[CS_ETMV4_PRIV_MAX] = {
+ [CS_ETMV4_TRCIDR0] = "trcidr/trcidr0",
+ [CS_ETMV4_TRCIDR1] = "trcidr/trcidr1",
+ [CS_ETMV4_TRCIDR2] = "trcidr/trcidr2",
+ [CS_ETMV4_TRCIDR8] = "trcidr/trcidr8",
+ [CS_ETMV4_TRCAUTHSTATUS] = "mgmt/trcauthstatus",
+};
+
static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu);

+static int cs_etm_set_context_id(struct auxtrace_record *itr,
+ struct perf_evsel *evsel, int cpu)
+{
+ struct cs_etm_recording *ptr;
+ struct perf_pmu *cs_etm_pmu;
+ char path[PATH_MAX];
+ int err = -EINVAL;
+ u32 val;
+
+ ptr = container_of(itr, struct cs_etm_recording, itr);
+ cs_etm_pmu = ptr->cs_etm_pmu;
+
+ if (!cs_etm_is_etmv4(itr, cpu))
+ goto out;
+
+ /* Get a handle on TRCIRD2 */
+ snprintf(path, PATH_MAX, "cpu%d/%s",
+ cpu, metadata_etmv4_ro[CS_ETMV4_TRCIDR2]);
+ err = perf_pmu__scan_file(cs_etm_pmu, path, "%x", &val);
+
+ /* There was a problem reading the file, bailing out */
+ if (err != 1) {
+ pr_err("%s: can't read file %s\n",
+ CORESIGHT_ETM_PMU_NAME, path);
+ goto out;
+ }
+
+ /*
+ * TRCIDR2.CIDSIZE, bit [9-5], indicates whether contextID tracing
+ * is supported:
+ * 0b00000 Context ID tracing is not supported.
+ * 0b00100 Maximum of 32-bit Context ID size.
+ * All other values are reserved.
+ */
+ val = BMVAL(val, 5, 9);
+ if (!val || val != 0x4) {
+ err = -EINVAL;
+ goto out;
+ }
+
+ /* All good, let the kernel know */
+ evsel->attr.config |= (1 << ETM_OPT_CTXTID);
+ err = 0;
+
+out:
+
+ return err;
+}
+
+static int cs_etm_set_option(struct auxtrace_record *itr,
+ struct perf_evsel *evsel, u32 option)
+{
+ int i, err = -EINVAL;
+ struct cpu_map *event_cpus = evsel->evlist->cpus;
+ struct cpu_map *online_cpus = cpu_map__new(NULL);
+
+ /* Set option of each CPU we have */
+ for (i = 0; i < cpu__max_cpu(); i++) {
+ if (!cpu_map__has(event_cpus, i) ||
+ !cpu_map__has(online_cpus, i))
+ continue;
+
+ switch (option) {
+ case ETM_OPT_CTXTID:
+ err = cs_etm_set_context_id(itr, evsel, i);
+ if (err)
+ goto out;
+ break;
+ default:
+ goto out;
+ }
+ }
+
+ err = 0;
+out:
+ cpu_map__put(online_cpus);
+ return err;
+}
+
static int cs_etm_parse_snapshot_options(struct auxtrace_record *itr,
struct record_opts *opts,
const char *str)
@@ -105,8 +197,9 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
container_of(itr, struct cs_etm_recording, itr);
struct perf_pmu *cs_etm_pmu = ptr->cs_etm_pmu;
struct perf_evsel *evsel, *cs_etm_evsel = NULL;
- const struct cpu_map *cpus = evlist->cpus;
+ struct cpu_map *cpus = evlist->cpus;
bool privileged = (geteuid() == 0 || perf_event_paranoid() < 0);
+ int err = 0;

ptr->evlist = evlist;
ptr->snapshot_mode = opts->auxtrace_snapshot_mode;
@@ -241,19 +334,24 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,

/*
* In the case of per-cpu mmaps, we need the CPU on the
- * AUX event.
+ * AUX event. We also need the contextID in order to be notified
+ * when a context switch happened.
*/
- if (!cpu_map__empty(cpus))
+ if (!cpu_map__empty(cpus)) {
perf_evsel__set_sample_bit(cs_etm_evsel, CPU);

+ err = cs_etm_set_option(itr, cs_etm_evsel, ETM_OPT_CTXTID);
+ if (err)
+ goto out;
+ }
+
/* Add dummy event to keep tracking */
if (opts->full_auxtrace) {
struct perf_evsel *tracking_evsel;
- int err;

err = parse_events(evlist, "dummy:u", NULL);
if (err)
- return err;
+ goto out;

tracking_evsel = perf_evlist__last(evlist);
perf_evlist__set_tracking_event(evlist, tracking_evsel);
@@ -266,7 +364,8 @@ static int cs_etm_recording_options(struct auxtrace_record *itr,
perf_evsel__set_sample_bit(tracking_evsel, TIME);
}

- return 0;
+out:
+ return err;
}

static u64 cs_etm_get_config(struct auxtrace_record *itr)
@@ -314,6 +413,8 @@ static u64 cs_etmv4_get_config(struct auxtrace_record *itr)
config_opts = cs_etm_get_config(itr);
if (config_opts & BIT(ETM_OPT_CYCACC))
config |= BIT(ETM4_CFG_BIT_CYCACC);
+ if (config_opts & BIT(ETM_OPT_CTXTID))
+ config |= BIT(ETM4_CFG_BIT_CTXTID);
if (config_opts & BIT(ETM_OPT_TS))
config |= BIT(ETM4_CFG_BIT_TS);
if (config_opts & BIT(ETM_OPT_RETSTK))
@@ -363,19 +464,6 @@ cs_etm_info_priv_size(struct auxtrace_record *itr __maybe_unused,
(etmv3 * CS_ETMV3_PRIV_SIZE));
}

-static const char *metadata_etmv3_ro[CS_ETM_PRIV_MAX] = {
- [CS_ETM_ETMCCER] = "mgmt/etmccer",
- [CS_ETM_ETMIDR] = "mgmt/etmidr",
-};
-
-static const char *metadata_etmv4_ro[CS_ETMV4_PRIV_MAX] = {
- [CS_ETMV4_TRCIDR0] = "trcidr/trcidr0",
- [CS_ETMV4_TRCIDR1] = "trcidr/trcidr1",
- [CS_ETMV4_TRCIDR2] = "trcidr/trcidr2",
- [CS_ETMV4_TRCIDR8] = "trcidr/trcidr8",
- [CS_ETMV4_TRCAUTHSTATUS] = "mgmt/trcauthstatus",
-};
-
static bool cs_etm_is_etmv4(struct auxtrace_record *itr, int cpu)
{
bool ret = false;
diff --git a/tools/perf/util/cs-etm.h b/tools/perf/util/cs-etm.h
index 0e97c196147a..826c9eedaf5c 100644
--- a/tools/perf/util/cs-etm.h
+++ b/tools/perf/util/cs-etm.h
@@ -103,6 +103,18 @@ struct intlist *traceid_list;
#define KiB(x) ((x) * 1024)
#define MiB(x) ((x) * 1024 * 1024)

+/*
+ * Create a contiguous bitmask starting at bit position @l and ending at
+ * position @h. For example
+ * GENMASK_ULL(39, 21) gives us the 64bit vector 0x000000ffffe00000.
+ *
+ * Carbon copy of implementation found in $KERNEL/include/linux/bitops.h
+ */
+#define GENMASK(h, l) \
+ (((~0UL) - (1UL << (l)) + 1) & (~0UL >> (BITS_PER_LONG - 1 - (h))))
+
+#define BMVAL(val, lsb, msb) ((val & GENMASK(msb, lsb)) >> lsb)
+
#define CS_ETM_HEADER_SIZE (CS_HEADER_VERSION_0_MAX * sizeof(u64))

#define __perf_cs_etmv3_magic 0x3030303030303030ULL

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